CVE-2026-71513
RCE in NLTK model unpickling allows arbitrary command execution
Is CVE-2026-71513 being exploited?
Not confirmed. CVE-2026-71513 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.78% probability of exploitation in the next 30 days.
How severe is CVE-2026-71513?
CVE-2026-71513 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-71513?
Yes. A fix has been recorded for CVE-2026-71513. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-71513 affect?
CVE-2026-71513 affects NLTK < 3.10.3, TransitionParser model files, allowlisted_pickle_load, Python pickle deserialization. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-71513?
Upgrade NLTK to >=3.10.3; do not load untrusted models; restrict model-loading privileges
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution when TransitionParser.parse loads crafted models via allowlisted_pickle_load; attacker can execute arbitrary commands as the process user.
Immediate action required
- affected>= 3.10.0 and < 3.10.3
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.